1. Technical Field of the Invention
The present invention relates to a power management method and a power management device, particularly to a power management method and a power management device for a display.
2. Description of the Related Art
FIG. 1 is a diagram of switching the refresh rate in the prior art. When a display is idle or in a static state and receives a static image notification, the workload can be reduced by decreasing the number of refreshing frame per second in order to decrease the refresh rate. For example, the refresh rate of the display can be reduced from 60 Hz (refresh 60 frames per second) to 5 Hz (refresh 5 frames per second). When the display receives the dynamic image notification, the refresh rate can be resumed from 5 Hz to 60 Hz. However, although reducing the refresh rate reduces the workload of the display, the amount of the saved energy is still limited because the source driver of the display is still in a standby status during the time intervals between each frame in low refresh rate.
In addition, after reducing the refresh rate, the sustaining time of a single frame is longer, and the leakage current generated by the manufacturing process of Thin-Film Transistor (TFT) leads to an inconsistent capacitance and voltage of the liquid crystal of the display, so that the flicker of display is more obvious to the user while watching.